Saws have a long history, and from its beginning to date, handsaws have been used by many people.
Meanwhile, electric power saws, which have been developed relatively recently, are electric power tools which cut wood and others with overwhelming horsepower supported by electric power. The same applies to chainsaws powered by engines. Although the electric power saws etc. having overwhelming power, so-called power saws, and the handsaws which cut using human power only, without relying on electric or or other power, are similar in that both use cutting teeth, in practice, they are considerably different in terms of concepts regarding their structures and functions, so they belong to substantially different technical fields.
FIG. 10 shows an example of a handsaw. A handsaw is generally made up of a grip 1, called a handle, and an elongated metal saw blade 2 attached to an end of the grip 1. A large number of teeth 3 are arranged on a longitudinal edge of the saw blade 2.
The handsaw shown in FIG. 8 (A), (B) is an example of the so-called ripsaw. The ripsaw is suitable for cutting wood along the grain. The ripsaw has a large number of triangular teeth 3 arranged on a longitudinal edge of the saw blade 2, and performs cutting with the distal ends of the triangular teeth 3 as cutting edges T. Each triangular tooth 3 has a base that constitutes a gullet or valley V together with the base of the adjacent triangular tooth 3. In the ripsaw, typically, the cutting edges T and the gullets V are aligned in the lateral direction, or, at a right angle with respect to the longitudinal direction of the saw blade 2.
The handsaw shown in FIG. 9 (A), (B) is an example of the so-called crosscut saw. The crosscut saw is suitable for cutting wood across the grain. In the crosscut saw, each triangular tooth 3 formed on a longitudinal edge of the saw blade 2 has sharp vertical cutting edges 3a, 3b provided on a pair of front and rear beveled portions on a distal end of the tooth. The vertical cutting edge denoted as 3a is in front with respect to a cutting direction D, and the vertical cutting edge denoted as 3b is at back with respect to the cutting direction D.
The vertical cutting edges 3a, 3b cut into the wood like knives, to sever the grain. The bases of adjacent triangular teeth 3 constitute a gullet V.
Some known crosscut saws have a cut end face 4, called “top edge” (“Uwame” in Japanese), formed by obliquely truncating a triangular tooth 3 near its distal end, and front and rear edges of the cut end face 4 serve as oblique horizontal cutting edges 4a and 4b. The cut end face 4 and the oblique horizontal cutting edges 4a and 4b can achieve the function of a ripsaw, or the function of, when cutting wood, carving and scraping off like a chisel, a part of the wood corresponding to the thickness of the saw blade 2.